1. Field of the Invention
The present invention relates to an organic electroluminescent device, and more particularly, to an organic electroluminescent device having a hole-blocking layer and a method for fabricating the same.
2. Discussion of the Related Art
Recently, with the trend of large sized display devices, demand for flat display devices occupying smaller space has been increased. An example of the flat display device is an organic electroluminescent device, also referred to as an organic light emitting diode (OLED). And, technology for the organic electroluminescent display is under rapid development, whereby various prototypes have been in market already.
The organic electroluminescent device is a light emitting device, whereby electric charges are injected in an organic layer formed between an anode and a cathode, so as to form a pair of electron and hole which generates an exciton, an excited state of which falls to a ground state, thereby emitting light.
The organic electroluminescent device is advantageous in that the device is formed on a flexible transparent substrate, such as plastic, and operated at a lower voltage (less than 10V), as compared to a plasma display panel or an inorganic electroluminescent display.
Also, the organic electroluminescent device requires less power consumption and provides a wide range of colors. Moreover, the organic electroluminescent device enables to express three colors including green, blue, and red. Therefore, the organic electroluminescent device is viewed and considered as the next generation full-color display device.
The organic electroluminescent device generates an exciton by coupling a hole from a hole transport layer with an electron form the hole transport layer, the exciton corresponding to a luminescent area.
However, the exciton can be generated by the fast transport speed of the hole in another area except the luminescent area.
The exciton generated in another area except the luminescent area illuminates in that area only, thus, there is a problem lowering color purity and brightness.
Therefore, for increasing the performance and the brightness of the device, a material blocking a movement of the hole needs to be formed around the luminescent layer.